Electrocatalytic oxidation of SO2 has been applied in many fields, and electrocatalyst is the focus of the research. Platinum-based electrocatalysts are the hot spot in this reaction. Although the properties of these materials have been optimized to a certain extent, there is still room for improvement in activity and long-term durability. In light of this, two kinds of carbon-supported Pt-Ru bimetallic electrocatalysts (PtRu/C alloy catalyst and Ru@Pt/C core-shell catalyst) were prepared by the microwave reduction method. The experiments demonstrate that the enhancement in the activity of bimetallic catalysts originates from the electronic effect and bifunctional effect between Pt and Ru. Bimetallic catalyst contains a large number of RuOxHy, which promotes the reaction. Because of the high Pt utilization, Ru@Pt/C catalyst with the Pt shell has a higher performance than alloy catalyst. The unit Pt mass activity of PtRu/C and Ru@Pt/C is 1.73 and 2.43 times that of Pt/C, respectively. Ru@Pt/C exhibits excellent stability in the high acid environment and is a promising SO2 electrocatalyst.